Filters have been employed in a variety of applications including hydraulic systems, fuel systems, and engine lubrication systems. Such filters may generally be spin-on type filters and include a filter element within a can or housing having a cover or attachment plate at one end by which the filter can be screwed onto or off of a filter head. A central opening and several surrounding openings in the cover are typically provided to direct flow through the filter and filter element therein, which flow can be either an inside/out or outside/in direction relative to the filter element. A circular gasket on the outside of the cover serves as the external seal between the filter and the filter head, while another circular gasket on the inside of the cover functions as an internal seal between portions of the filter element and the cover. Spin-on filters are usually used only once before removal and replacement.
Eventually, the filter element becomes clogged requiring replacement of the filter. However, it is not always easily known when it is appropriate to change the filter. Sometimes, the filter element becomes clogged, and the fluid to be filtered backs up and causes problems in the system. Also, it can stop fluid flow to downstream system components. Because of this, in addition to problems created during cold starts and flow surge conditions, bypass valves have been equipped in the filter head. When the pressure in the spin-on filter exceeds a certain amount due to, for example, a clogged filter element, a cold start condition, or a flow surge, the bypass valve opens and permits fluid to continue downstream through the system. This can be problematic, as it allows completely unfiltered fluid which may have substantial contaminants therein to pass through the system. This can lead to transmission problems and/or damage to the components of an internal combustion engine.